Genetic Mapping of Qunatitative Trait Loci in Maize in Stress and Nonstress Environments: II. Plant Height and Flowering
The utility of restriction fragment length polymorphisms (RFLPs) in mapping quantitative trait loci (QTL) has been established in elite maize (Zea mays L.) populations, hut the ability to consistently detect QTL in diverse environments has not been assessed. QTL mapping studies conducted in diverse environments could be a means of locating genes which respond to stress conditions and could provide further understanding of some types of genotype × environment interaction. Our objectives were to investigate the ability to detect QTL for flowering and plant stature traits in two diverse environments and to assess the genetic relationship of QTL for correlated traits. A single-cross of elite inbreds Mo17 and H99 was used to produce a population of 150 F2:3 lines. Traits were measured on replicated progeny grown in two climatically diverse years at the same location, in which one year was an average environment, and the other year was a stress environment. QTL determinations were made in each environment and the mean of the two environments by using a linkage map of 111 loci. About 50% of all QTL were detected in both environments. The location and parental contribution of these QTL were consistent, hut their effects varied in size. More QTL were identified in the stress environment for anthesis and silk emergence, but the other traits had equivalent numbers of QTL detected in each environment. All QTL identified in the nonstress environment and all QTL identified in the stress environment were also detected in the mean environment. Correlations between traits were generally reflected in the similarity of locations and parental contributions of QTL for these traits. The exception was anthesis and anthesis-to-silking interval, which had QTL in common but very poor correlation. The locus of a probe for an1, a plant height mutant, was most closely associated with the QTL having the largest effect on plant height. This finding contributes to the supposition that quantitatively and qualitatively inherited traits share a common set of loci with alleles of varying magnitude of effects.
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